Applying an integrated exploration strategy requires two basic steps: - Establishment of database, containing the given observations - Development of model data base The model here is defined as a tool to aid in organizing the given observations, and contains interrelated subgroups of detailed submodels. These submodels may be facies trends, velocity models, maps resulting from global log-correlations etc. Therefore the development of the submodels comprises the following steps: - Global basin analysis (uplift/subsidence, basin history, hydrocarbon potential, migration paths, trapping etc.) - Structural interpretation/sequence analysis of the given seismic data (2D or 3D), integration of non seismic-data likegravity, magnetics - Classification of intervals, facies trends for selected intervals, mapping of additional tops etc (AB/C-code), application of geostatistics. - Refinement/extension of mapped interfaces - Final depthing using improved velocity functions - Application of modeling tools / special processing techniques to improve resolution / verify interpretation In this article we discuss some aspects of carbonate settings being evaluated along above guidelines, where the following items are investigated: - identification of build ups - mapping of shelf trends - application of special processing tools such as L1-decon, AVO-analysis etc. - verification of shelf trends in terms of lithofaciesunits, i.e., their individual impedance values, by finite-difference forward modeling (e.g., zero-offset application). - Derivation of final velocity model for time-depth conversion. The final result of the seismostratigraphic work allows an evident increase of effectiveness in hydrocarbon evaluation and production due to the detailed knowledge of lithofacies trends, lateral and vertical as well as estimates of the permeability distribution, possible local permeability barriers and sealing potential. The chronostratigraphic information content of seismic sequence analysis allows in addition for an improved well-to-well correlation. This remark is especially valid for 3D data and the resulting 3D stratigraphic model, which forms the basis for a reservoir model.
Integrated exploration strategy in the sense of this article is summarized in Fig. 1, i.e., ft is defined as the integration of structural and stratigraphic interpretation with interactive feedback using the same data base. This concept is applied to carbonate environments. A schematic cross section for marine carbonate deposition is shown in Fig. 2 (Pettijohn, 1975). In general, there are five groups of modern carbonate deposits: - shallow water marine deposits - deep-water marine deposits - carbonates of evaporitic basins - carbonates of freshwater lakes/springs - eolian carbonates. The shallow water environment is itself complex and includes tidal and supratidal flats, more extensive shelf and bank areas, marginal reefs, and back reef-lagoons. Using a data example from Africa, the integrated exploration strategy is discussed in detail.